Transcriptional regulation has been the main focus for gene regulation in the past. However, a tremendous amount of evidence from recent studies also indicates that translational regulation plays a key role during development, cell cycle control, and mechanisms related to acute drug resistance. Gene expression analysis on actively translated mRNA transcripts provides a unique approach to study post transcriptional regulation. Previous studies have relied on a traditional sucrose gradient ultracentrifugation procedure to isolate polysome complexes and requires a large amount of cells (up to 500 million cells). As a result, this still remains a major bottleneck for the investigation of post transcriptional regulation with limited quantities of clinical samples. Therefore, there is an urgent need to develop a novel approach to isolate actively translated polysomes from a small number of cells (10 to 500 cells). The new approach will allow us to systematically study potential translational regulation with limited clinical samples. It has been shown that actively translated mRNAs are associated with multiple units of ribosomes and the newly synthesized polypeptides are closely associated with molecular chaperones such as hsp73. These molecular chaperones assist in the proper folding of nascent polypeptides into higher ordered structures. These chaperones will provide the anchor to separate actively translated mRNAs associated with polysomes from free mRNAs. Affinity antibody capture beads will be developed to capture hsp73 chaperones associated with the polysome complexes so that all polysomes can be separated from monosomes and free mRNAs. The isolated actively translated mRNAs will be used for high throughput gene expression analysis. The specific aims of the proposed project are: 1.) Develop antibody conjugated affinity capture magnetic beads and conditions to capture actively translated mRNAs associated with the polysome complex from a small number of cells. 2.) Validate the antibody affinity capture approach for polysome isolation by comparing with traditional polysome isolation protocols via quantitative RT-PCR gene expression analysis. 3.) Identify potential translationally regulated genes that are responsible for determining chemosensitivity during 5- fluorouracial (5-FU) treatment from human colon cancer samples. [unreadable] [unreadable] [unreadable]